The proposed research will examine the association between child care quality and child cognitive, behavioral and health outcomes focusing on new domain-specific (cognition, behavior, health) measures of quality. Although prior studies find that child care quality is significantly and positively associated with measures of child development, the effect sizes reported in studies that used large, secondary datasets are modest. These modest effect sizes may be explained, in part, by the use of global ratings of quality of care that ignore the domain-specificity of child care quality emphasized by developmental theory and small-scale intervention studies, which find larger effects. We hypothesize, for example, that direct measures of language stimulation are more strongly associated with language development than global quality measures that include items relevant to other domains such as health and safety practices. Notably, studies that use global quality measures have caught the attention of the media and policymakers and are likely to be influential in determining future policy in this area (Layzer and Goodson, 2006). The proposed research will create new, domain-specific measures of child care quality using four large-scale surveys: Early Childhood Longitudinal Study-Birth Cohort; NICHD Study of Early Child Care and Youth Development; Early Head Start Research and Evaluation Project; and the Embedded Development Study from Welfare, Children and Families: A Three City Study. Although these datasets contain a large array of items on child care quality, this detailed information has not been exploited to create domain-specific measures of child care quality. We will use these items and appropriate psychometric methods to construct measures of child care quality specific to health (e.g., motor development, common illness), approach to learning (e.g., attention, enthusiasm, persistence), as well as the more commonly studied cognitive and socio-behavioral domains. The health and learning domains have been relatively neglected in social science research (Zaslow et al., 2006). Where necessary, we will also examine the psychometric properties of non-cognitive measures of child development because the reliability and validity of some of these outcomes are less established than is the case for cognitive outcomes (Zaslow et al., 2006). Several current policy and research debates underscore the importance of the proposed research. For example, children who have spent time in child care centers versus family day care homes are more academically prepared for school, on average, but they have higher rates of behavior problems at school entry (Loeb et al., 2007; Magnuson et al., 2007; NICHD 2007). Children in centers are also more likely to catch contagious diseases (Gordon, Kaestner & Korenman, 2007; NICHD 2003b). And, there is some evidence that injury rates are higher in unregulated home-based care (Currie and Hotz, 2004; Wrigley and Dreby, 2005). Domain- specific measures of quality may help explain these different effects of center- and home-based child care, as the type may simply be a proxy for average differences in aspects of the quality of care. The broad objective of our research is to assess the strength of the associations between domain-specific aspects of the quality of child care and child outcomes. Within this broad objective, we address the following specific research questions for cognitive, behavioral, and health outcomes: Cognition: Do measures of quality conceptually linked to cognition explain the higher average cognitive outcomes for children cared for in centers versus homes? Are the effect sizes of domain-specific quality on cognitive outcomes in community-based care closer to those of model interventions, in contrast to effect sizes reported in prior studies using global quality? Are domain-specific qualities of child care associated with approaches to learning and math skills? Behavior: Do measures of quality aligned specifically to social competence and emotional regulation explain the elevated behavior problems observed among children who spend long hours in large group care? Health: Are health-specific aspects of child care quality associated with child health. For example, are materials and opportunities for motor activities associated with better motor development and better overall health? Is disease spread reduced to the lower levels seen in homes when community-based centers use stringent infection control practices?